The Sun, Seasons and Global Warming
Let’s talk about the Sun and its’ possible impact on weather and climate.
On January 4, co-incidentally when this article appears, the Sun will be at its closest point to Earth at any time during the year. Yes, it is hard for those of us living in the northern hemisphere to believe that the Sun will be actually 3.1 million miles closer to us than in July when we are enjoying summer, but that indeed is the case.
The diagram from Wikipedia, somewhat exaggerated to illustrate the elliptical nature of Earth’s orbit and this concept, shows the Sun [number 3] and the Earth on January 4 [number 2] and on July 6 [number 1].
For those science buffs around us, when Earth is at location 1 in its orbit around the Sun it is called aphelion, and when it is at location 2, it is called perihelion.
So what explains the cold weather we get in our winter if we are so much closer to the Sun? The reason is that Earth has an axial tilt of about 23.4 degrees and so the Sun’s rays do not strike the North Country as directly at this season as it does in the summer; our days are shorter and the Sun is lower in the sky.
So these circumstances are all more or less normal and part of our annual weather cycle.
Another solar variable that we all experience, but probably few notice, is the sun-spot cycle of 11 years that is observed on the solar surface. A photo of the Sun shows some of these sunspots, with a large cluster above center.
Because of their visibility on Earth, observers and scientists have been following the coming and going of these spots for centuries. A fairly good record exists from about 1600 forward but Chinese astronomers were regularly recording some of this data as early as 28 BC.
So why the interest in sun-spots?
Attempts have been made to link sunspot activity with global climate, not just weather. The Maunder Minimum [see “400 Years of Sunspot Observations”] when very few spots were observed, was a real event and happened to coincide with the middle part of a period called the “Little Ice Age” that gripped parts of Europe. This period also had some very warm years as well however, and data is not available to show that this solar event, called Maunder Minimum, had global long term climate effects.
Available data suggests that another cold period occurred around the interval called the Dalton Minimum. Again, in looking at the peaks and valleys of sunspot activity at that time there appears to be no correlation with the weather experienced. Some of the peaks and valleys are much the same as we are experiencing today when we are breaking global heat records.
Indeed sunspot maxima do correspond with increased solar wind, aurora, magnetic storms, solar flares and such. Similarly, during sunspot minima the Sun is quieter with less of these phenomena.
Reference another chart labeled “Cycle 24 Sunspot Number Prediction” which has more detail. This graph also shows Cycles 22 and 23 for comparison purposes. Let’s focus for a moment on these 3 cycles.
What is of interest from a “Climate” point of view is the fact that the recent sunspot minima, or maxima, all occur during the warmest years in the historical record.
Observe the graph labeled MetOffice. This data is from the Meteorological Office in England and illustrates the hottest 50 years in the climate record from the warmest on the left to the coolest on the right.
What is startling is that all 14 years since 2000, together with 1998, are the warmest in the last 140 years. The sunspot data, maxima or minima, suggest no correlation of sunspot number with global temperatures.
However, increasing amounts of the greenhouse gas, CO2, in air, does correlate with the increase of Earth’s temperature.
This clear correlation is in Jim Hansen’s [climatologist] blog entry of 12/23/14. It shows the “Annual Fossil Fuel CO2 Emissions” increasing, and the resulting “CO2 Appearing in Air” increasing. Some CO2 ‘disappears’ into the oceans or biosphere.
Increased global temperatures are moving in lockstep with these emissions.
It is CO2 emissions that are causing climate change.
The scientific career of Raymond N. Johnson, Ph.D., spanned 30 years in research and development as an organic/analytical chemist; he is currently founder and director of the Institute of Climate Studies USA (www.ICSUSA.org). Climate Science is published the first Sunday of every month.